Spray valve actuating mechanism for diesel engines



Dec. 24, 1935. J, Q OETZEL 2,025,245

SPRAY VALVE ACTUTING MECHANISM. FOR DIESEL ENGINES Filed June '9, 1951 A TTORNEYS.

Patented Dec. 24, 1935 PATENT OFFICE SPRAY VALVE ACTUATING MECHANISM FOR DIESEL ENGINES fj f John George Oetzel, Alameda, Calif., -assignor to Atlas Imperial Diesel Engine Company, Oakland, Calif., a corporation of Delaware Application June 9, 1931, Serial No. 543,142

2 Claims.

This invention relates to engines operating on the Diesel cycle and particularly pertains to the spray valve actuating mechanism thereof.

I-litherto, in Diesel engines operating with a mechanical spray valve, the spray valve spring was ordinarily the sole agent for overcoming the inertia of the push rod and connecting mechanism between the same and the spray valve. It

, has been found that this is insufcient to maintain the cam follower in proper position relative to the operative portion of the cam over the period of injection. Therefore, it is the principal object of the present invention to provide means for neutralizing the inertia of the spray valve actuating parts and for maintaining the cam follower in contact with the cam rise during the period of valve opening without subjecting the cam and associated parts of the valve operating gear to any additional pressure during the inoperative period of its cycle of operation whereby to eliminate excessive wear and accompanying disadvantages. By thus insuring that the cam follower is maintained in proper contact with the cam rise during the period of injection, accuracy in time and duration of injection is insured.

By eliminating wear in the spray valve cam operating mechanism, smoother and more efficient operation of the engine is obtained.

One form which the invention may assume is exemplified in the following description and illustrated by way of example in the accompanying drawing, in which:

Fig. l is a fragmentary view in elevation and section of a spray valve actuating gear of a Diesel engine, embodying my invention.

Fig. 2 is a View in elevation and section of a portion of the spray valve actuating gear shown in Fig. 1.

Fig. 3 is a diagrammatic view showing the manner in which the push rod is guided in the follower.

Referring more particularly to the accompanying drawing, I have illustrated a spray valve assembly I which may be of any preferred design which is mechanically operated. 'I'he valve stem proper is operated by a rocker arm II which in turn is actuated by a rocker arm I2. One end of the rocker arm I2 is operatively connected as at I4 to a depending push rod I5. The lower end of this push rod I5 projects within a guide formed in a valve lifter IB. This valve lifter I6 is mounted for vertical reciprocation in a casting I'I bolted or otherwise secured to the engine frame I8. The lifter I6 is guided for vertical reciprocation in the 55 casting I'I and is held from rotation by any suit- (Cl. 12S-90) able means. The lower end of the lifter I6 is tted with a cam follower I9 to engage the injection cam 2B operated in synchronism with the engine crankshaft.

Intermediate its ends the lifter I6 is formed with a transverse aperture in alignment with which is an aperture in the casting Il. These apertures are for the purpose of accommodating a wedge ZI which projects horizontally from a wedge arm 22 secured on the wedge shaft 23 of the engine. This mounting of the wedge enables it to be inserted or withdrawn as desired by oscillation of the wedge shaft. The position of the wedge determines, as in standard practice, the lift of the spray valve. 15

At a point above its lower end, the push rod is formed with a circumscribing collar 2d and interposed between this collar 24 and the uppermost end of the lifter I6 is a comparatively light spring 25. The function of this spring is, of course, to 20 normally maintain the lifter I6 in a position where the roller I5 will ride on the periphery of the injection cam 2li. This spring also serves the function of maintaining a proper gap between the lower extremity of the push rod i5 and the point 25 of contact 26 between the lifter i6 and the wedge 2i. This point of contact 26 is provided by the insertion of a hardened cylindrical piece suitably fixed within the lifter at the bottom of the aperture which extends transversely through the lifter. 30 The hardened cylindrical piece is adapted to engage the lower surface of the wedge 2i while the upper surface of the wedge is adapted during the period of operation to engage the lower extremity of the rod. The spring 25 maintains the gap be- 35 tween the push rod and the point of contact 26 constant during the period when the valve is idle so that the wedge is free for movement during this period to relieve thegovernor of excessive strain.

However, it has been found that when the cam roller I9 is engaged by the toe or rise of the cam, the lifter I6 and the push rod are moved rapidly upwardly and due to the acceleration which creates an inertia force and unless this is 45 dampened the roller will leave the toe of the cam at the highest point thereon and. will not follow the same during the decline of the toe. In order to dampen this acceleration and overcome the inertia of the parts and thereby main- 50 tain the roller I9 in rm contact with the toe of the cam throughout its rise and decline and thereby insure accurate time and duration of opening of the injection valve, I have provided an auxiliary spring 28. This spring is mounted in a cage 29 arranged ccncentrically about the push rod I5. The lower end of this cage is reduced in diameter and threaded into the upper end of the casting I'l so that the point on the cam that this spring becomes effective may" be varied with respect to the high point of the cam.

It should be stated that the spring 28 is placed under initial compression to neutralize the initial inertia force set up upon engagement of the cam roller I 9 with the toe of the cam. The spring is so calculated that it follows the inertia curve so as to entirely compensate for the inertia set up in the moving parts `of the spray valve actuating mechanism throughout their cycle of operation during the rise and fall of the toe of the cam. Therefore, it is obvious that as the Y cam roller I9 commences to rise on the toe of the cam 20, the spring 28 will tend to be cornpressed and in such a manner that the roller I9 will be held in constant contact with the toe of thecam 2B. `|Thus accuracy of timing and duration of injection will be insured. Also, the provision of this spring 28 relieves the spring in the spray valve assembly of overcoming the inertia of the reciprocable and oscillating partsl of the connection between the injection valve and the cam.

It should be pointed out, however, that by adjusting the cage 25 relative to the casting I1 that the point at which the spring 28 comes into operation may be varied with respect to the high point on the toe of the cam 25J. In other words, if the cage 29 is lowered with respect to the casting I'I through the medium, of the threaded connection therebetween, the spring will come into operation at a period more advanced with respect to the high point of the cam and will remain in operation 'for a longer period after the high point has been passed. However, should the cage 2B be elevated with respect to` the casting I'I, the period at which the spring 28 comes into operation and is .relieved from operation with respect to the high point of the cam is reduced. This adjustment may also be utilized to compensate for slight variations occasioned by manufacture of the engine and also to compensate for wear between the various parts naturally resulting through continued operation.

I also want to point out that the lower end of the push rod which is guided in the lifter I6 is provided with a spherical portion 30 which engages the guiding surface within the lifter I6. The lower extremity of the push rod is also partially spherical and formed from the same cen- 5 ter as the spherical portion 30 which engages the guide surface in the 'lifter I6. The purpose of this is to prevent any slight misalignment between the push rod and the lifter I6 from creating a binding action between the bearing sur- 10 face between the two and also prevent any such misalignment or deflection in the push rod I5 from varying the gap between the lower extremity of the push rod and the contact point 26.

While I have shown the preferred form of my invention, it is to be understood that various changes may be made in its construction by those skilled in the art without departing from the spirit of the invention, as defined in the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent\is:

l. In an internal combustion engine having a spray valve, a cam, and a connecting mechanism associated with the cam and the spray valve for actuating the latter from the cam, a stationary cage, a push rod included in said mechanism and reciprocable through the cage, a lifter associated with the push rod and with the cam, a spring within said cage, said cage holding said spring under initial compression without exerting the spring force on the push rod during inoperative periods thereof, means on the push rod engaging the spring whereby the latter will be eective when the latter is operated to overcome inertia set up incident to operation of the push rod and the remainder of said connecting mechanism.

2. In a valve actuating mechanism of the character described, a reciprocable rod, a wedge ent gaging an end of the rod to adjust the reciprocable movement thereof, a guide surrounding the rod, an enlarged portion on the rod engageable with the inner wall of the guide, the surface of said enlarged portion and the end of the rod engaged by said wedge being spherical in contour and having a common center.

JOHN GEORGE OETZEL. 

